Sungevity, a fast-growing solar energy company, has signed a deal to move its headquarters and 54 employees — with expectations of hiring dozens more — from Berkeley to downtown Oakland’s Jack London Square.

“We are growing pretty fast,” said Danny Kennedy, president and co-founder of Sungevity. “We have doubled our head count over the last year.”

The number of employees could grow even more rapidly.

“We expect to get to 75 employees by May or June,” Kennedy said.

Sungevity agreed to rent 19,000 square feet at 66 Franklin St. in a deal arranged by Cornish & Carey, a commercial realty brokerage.

When Sungevity moves into its new offices Monday, the seller of solar energy systems will become the latest company in Jack London Square, an increasingly bustling district that is undergoing a $375 million renovation by developers Ellis Partners and Transbay Holdings.

“This deal is great because it puts more people into the local market,” said Bill Nork, a senior vice president with Cornish & Carey. “You will have more people who will eat in the restaurants, shop, enjoy the dining district and the night life there.”

The building is a one-time ice warehouse that used to house The Old Spaghetti Factory. Bocanova restaurant and Miette Bakery are on the ground floor of the renovated building.

“We’re excited to welcome a dynamic, growing business focused on renewable energy,” said Jim Ellis, managing principal of Ellis Partners.” Sungevity is an ideal fit for us.”

Sungevity will retain its current 6,000 square feet of offices in Berkeley. The company will maintain its installation operations there, Kennedy said.

The company, which had $5 million in sales during 2009, is expecting “substantial growth in revenues,” Kennedy said.

And the size of its new building could conceivably accommodate even more employees than the 75 who might be working for Sungevity by this summer.

The company’s online site lists 17 current openings. They are in accounting, administration, computers and software, customer service, sales and solar design.

What about an initial public offering? Sungevity has raised more than $9 million in venture capital and first-stage angel financing.

“It’s always our objective to be ready for an IPO but not for a few years,” Kennedy said. “Our investors are very excited about our growth trend.”

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